Fix redirect paths and error messages for submissions.
Fix redirect paths and error messages for submissions.

peterkshultz/gradecraft-development,peterkshultz/gradecraft-development,UM-USElab/gradecraft-development,zqian/gradecraft-development,UM-USElab/gradecraft-development,zqian/gradecraft-development,mkoon/gradecraft-development,mkoon/gradecraft-development,peterkshultz/gradecraft-development,mkoon/gradecraft-development,UM-USElab/gradecraft-development,zqian/gradecraft-development,UM-USElab/gradecraft-development